#endif
#include <pulsecore/macro.h>
-#include <pulsecore/mutex.h>
#include "once.h"
-pa_bool_t pa_once_begin(pa_once *control) {
+/* See http://www.hpl.hp.com/research/linux/atomic_ops/example.php4 for the
+ * reference algorithm used here. */
+
+bool pa_once_begin(pa_once *control) {
+ pa_mutex *m;
+
pa_assert(control);
if (pa_atomic_load(&control->done))
- return FALSE;
-
- pa_atomic_inc(&control->ref);
+ return false;
/* Caveat: We have to make sure that the once func has completed
* before returning, even if the once func is not actually
* executed by us. Hence the awkward locking. */
- for (;;) {
- pa_mutex *m;
-
- if ((m = pa_atomic_ptr_load(&control->mutex))) {
-
- /* The mutex is stored in locked state, hence let's just
- * wait until it is unlocked */
- pa_mutex_lock(m);
-
- pa_assert(pa_atomic_load(&control->done));
-
- pa_once_end(control);
- return FALSE;
- }
-
- pa_assert_se(m = pa_mutex_new(FALSE, FALSE));
- pa_mutex_lock(m);
-
- if (pa_atomic_ptr_cmpxchg(&control->mutex, NULL, m))
- return TRUE;
+ m = pa_static_mutex_get(&control->mutex, false, false);
+ pa_mutex_lock(m);
+ if (pa_atomic_load(&control->done)) {
pa_mutex_unlock(m);
- pa_mutex_free(m);
+ return false;
}
+
+ return true;
}
void pa_once_end(pa_once *control) {
pa_assert(control);
+ pa_assert(!pa_atomic_load(&control->done));
pa_atomic_store(&control->done, 1);
- pa_assert_se(m = pa_atomic_ptr_load(&control->mutex));
+ m = pa_static_mutex_get(&control->mutex, false, false);
pa_mutex_unlock(m);
-
- if (pa_atomic_dec(&control->ref) <= 1) {
- pa_assert_se(pa_atomic_ptr_cmpxchg(&control->mutex, m, NULL));
- pa_mutex_free(m);
- }
}
/* Not reentrant -- how could it be? */